# Two congruent triangles can be arranged to compose a parallelogram

I can explain how two congruent triangles can arranged to compose a parallelogram.

# Two congruent triangles can be arranged to compose a parallelogram

I can explain how two congruent triangles can arranged to compose a parallelogram.

## Lesson details

### Key learning points

- The area of a triangle is equal to half the area of the parallelogram you create from 2 congruent triangles.
- Any parallelogram can be decomposed into two congruent triangles.

### Common misconception

If pupils do not cut a parallelogram from vertex to opposite vertex, they will end up with either two non-congruent shapes or two congruent quadrilaterals.

Modelling is key and this is a useful time to revisit the concept of a shape's diagonal, that is, a line connecting vertex to a non-adjacent vertex.

### Keywords

Congruent - If one shape can fit exactly on top of another using rotation, reflection or translation, then the shapes are congruent.

Parallelogram - A parallelogram is a quadrilateral with two pairs of parallel and equal sides.

### Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

## Video

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## Starter quiz

### 6 Questions

Three equal sides.

Two equal sides and one different.

No equal sides.

One pair of perpendicular sides.